Let $$\begin{array} { l }
U = \{ 1,2,3,4,5,6,7 \} \
A = \{ 4,5,6,7 \} \
B = \{ 2,3,5,7 \} \
C = \{ 4,6,7 \}
\end{array}$$ List all the members of the set. $\bar { A }$
A) $\{ 1,2,3,4,5,6,7 \}$
B) $\{ 4,5,6,7 \}$
C) $\{ 1,2,3 \}$
D) $\{ 1,4,6 \}$
E) $\varnothing$

Question

Let $$\begin{array} { l } 
U = \{ 1,2,3,4,5,6,7 \} \
A = \{ 4,5,6,7 \} \
B = \{ 2,3,5,7 \} \
C = \{ 4,6,7 \}
\end{array}$$ List all the members of the set. $\bar { A }$
A) $\{ 1,2,3,4,5,6,7 \}$
B) $\{ 4,5,6,7 \}$
C) $\{ 1,2,3 \}$
D) $\{ 1,4,6 \}$
E) $\varnothing$

Quizplus · Accepted Answer

$\bar A$ contains all elements that are in $U$ but not in $A$. Thus, we can eliminate all elements in $A$ from $U$ to get $\bar A$.

$\bar A = \{1,2,3,4,5,6,7\} - \{4,5,6,7\} = \{1,2,3\}$

Therefore, the answer is choice C.

Let U={1,2,3,4,5,6,7}A={4,5,6,7}B={2,3,5,7}C={4,6,7}\begin{array} { l } U = \{ 1,2,3,4,5,6,7 \} \\A = \{ 4,5,6,7 \} \\B = \{ 2,3,5,7 \} \\C = \{ 4,6,7 \}\end{array}U={1,2,3,4,5,6,7}A={4,5,6,7}B={2,3,5,7}C={4,6,7}​

Let $\begin{array} { l } U = \{ 1,2,3,4,5,6,7 \} \\A = \{ 4,5,6,7 \} \\B = \{ 2,3,5,7 \} \\C = \{ 4,6,7 \}\end{array}$